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  • 1
    Electronic Resource
    Electronic Resource
    Heterogeneity in the Membrane Current Pattern of Identified Glial Cells in the Hippocampal Slice (1992)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 4 (1992), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Glial cells, acutely isolated or in tissue culture, have previously been shown to express a variety of voltage-gated channels. To resolve the question whether such channels are also expressed by glial cells in their normal cellular environment, we have applied the patch-clamp technique to study glial cells in hippocampal slices of 10–12-day-old mice. Based on the membrane current pattern, we distinguished four glial cell types. One was characterized by passive, symmetrical K+ currents activated in depolarizing and hyperpolarizing directions. A second population showed a similar current pattern, but with a marked decay of the current during the 50-ms voltage jumps. In a third population, the decaying passive currents were superimposed with a delayed rectifier outward current and, in some cases, with a slow inward current activated by depolarization. The fourth population expressed delayed rectifying outward currents, an inward rectifier K+ current and fast inward currents activated by depolarization. To unequivocally identify the glial cells we combined electrophysiological and ultrastructural characterizations. Therefore, cells were filled with the fluorescent dye lucifer yellow during characterization of their membrane currents, the fluorescence of the dye was used to convert diaminobenzidine to an electron-dense material, and subsequently slices were inspected in the electron microscope. Recordings were obtained from cells in the stratum radiatum and were identified as glial by their size, the characteristic chromatin distribution, and the lack of synaptic membrane specializations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1992.tb00897.x
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  • 2
    Electronic Resource
    Electronic Resource
    Recovery of ChAT lmmunoreactivity in Axotomized Rat Cholinergic Septal Neurons Despite Reduced NGF Receptor Expression (1997)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 9 (1997), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Previous studies have suggested that target-derived nerve growth factor (NGF) is essential for the survival of cholinergic basal forebrain neurons. Thus, axotomy of septohippocampal neurons in adult rats resulting in the withdrawal of target-derived NGF caused a dramatic loss of choline acetyltransferase (ChAT)-immunoreactive neurons in the medial septum-diagonal band complex. We have recently shown that this loss of immunolabelled neurons does not indicate cell death, since many septohippocampal cholinergic neurons recover their immunoreactivity for ChAT after a long survival time despite disconnection from target-derived neurotrophins. One possibility would be that these surviving ChAT-immunoreactive neurons have gained access to other, probably local, NGF sources. Here we provide evidence that the recovery of ChAT immunoreactivity after axotomy is not accompanied by a similar recovery of NGF receptor expression in these neurons. In situ hybridization for p75NTR mRNA and trkA mRNA 6 months after bilateral fimbria-fornix transection revealed a substantial loss of labelled cells. In addition, there was a persisting loss of p75NTR-immunoreactive and NGF-immunoreactive medial septal neurons. Cholinergic neurons in controls did not express NGF mRNA, but were heavily immunostained for NGF protein due to receptor-mediated uptake. These data suggest that at least some cholinergic septohippocampal neurons re-express ChAT either independently of NGF or with a reduced need for NGF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1997.tb01488.x
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of calcium in the myocardium of cardiomyopathic Syrian hamsters
    Amsterdam : Elsevier
    Journal of Molecular and Cellular Cardiology 20 (1988), S. 753-762 
    Details
    ISSN: 0022-2828
    Keywords: Calcium distribution ; Cardiomyopathic hamster ; Cytochemistry ; Mitochondria ; Sarcolemma
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0022-2828(88)80019-1
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  • 4
    Electronic Resource
    Electronic Resource
    Transneuronal effects of entorhinal lesions in the early postnatal period on synaptogenesis in the hippocampus of the rat (1977)
    Springer
    Experimental brain research 30 (1977), S. 549-560 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampus ; Synaptogenesis ; Entorhinal lesion ; Transneuronal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The granule cell axons of the dentate gyrus (mossy fibers, MF) terminate with large, characteristic boutons on neurons of the regio inferior of the hippocampus. To study transneuronal effects on mossy fiber synaptogenesis, the entorhinal cortex, which is the source of the main afferent to the granule cells, was removed in 3-day old rats. After a postoperative survival time of 27 days, the animals were killed and the brain prepared for electron microscopy. No clear postlesional changes were observed in the inner structure of the presynaptic mossy fiber terminals. The mean size of MF boutons was roughly the same in the experimental animals as compared to normal, unoperated rats of the same age (4.19 μm2, SD 1.9; and 4.29 μm2, SD 2.2, respectively). On the postsynaptic side, however, some remarkable changes were found. In the operated animals, the number and total area of dendritic spines in synaptic contact with MF has significantly decreased in comparison with the controls. Also the size of a single spine in the operated animals was only 64 % of that in the normal. These changes were accompanied by a decrease in MF total perimeter and MF-dendritic contact length in the experimental animals. The length of the MF specialized synaptic contact was found to be correlated with the number and size of dendritic spines. Thus accordingly, though the length of the MF specialized contact with the dendritic shaft did not change, the absolute length of MF specialized contact with postsynaptic spines was decreased in the lesioned animals due to the numerical and size reduction of the spines. This suggests that normally functioning entorhinal afferents to the granule cells are necessary for the normal development of dendritic spines in contact with hippocampal mossy fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237644
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  • 5
    Electronic Resource
    Electronic Resource
    Organization of identified fiber tracts in the rat fimbria-fornix: an anterograde tracing and electron microscopic study (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 481-493 
    Details
    ISSN: 1432-0568
    Keywords: Phaseolus vulgaris-leucoagglutinin ; Hippocampus ; Septum ; Entorhinal cortex ; Limbic system ; Fimbria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The fimbria is a major route for afferent and efferent fibers of the hippocampal formation. However, little is known about the intrinsic organization of the fimbria-fornix complex. In this study, the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHAL) was used to analyze the ultrastructure and topography of identified fiber tracts within the fimbria-fornix. Septo-hippocampal fibers are loosely distributed throughout the fimbria-fornix. Commissural fibers cross the midline in the ventral hippocampal commissure and form a tight fiber bundle in the fimbria. Crossed entorhino-hippocampal fibers cross the midline in the ventral hippocampal commissure rostral to the commissural fiber bundle, and crossed entorhino-entorhinal fibers pass through the dorsal hippocampal commissure. This suggests a topographical organization of fiber tracts within the fimbria-fornix that reflects the laminar organization of the hippocampal target structure: fibers of the diffusely terminating septohippocampal projection are loosely distributed throughout the fimbria-fornix, while those projections that are known to terminate in specific laminae of the hippocampal formation (commissural projection, crossed entorhino-hippocampal projection) form fiber bundles within the fimbria and the ventral hippocampal commissure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185879
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  • 6
    Electronic Resource
    Electronic Resource
    CCK-immunoreactive terminals form different types of synapses in the rat and monkey hippocampus (1988)
    Springer
    Histochemistry and cell biology 88 (1988), S. 343-352 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electronmicroscopic immunocytochemical analysis of the types and patterns of synaptic contacts formed by cholecystokinin (CCK)-containing terminals in the CA1 and CA3 region of the rat and monkey hippocampus reveals numerous symmetric synaptic contacts on cell bodies and dendritic shafts of pyramidal cells in both species. In the monkey, however, CCK-immunoreactive terminals also form asymmetric synaptic contacts with dendritic spines, such contacts are absent or very rare in the rat hippocampus. The present finding in primate hippocampus provides evidence that the same neuropeptides can be found in both symmetric and asymmetric contacts and may be added to other evidence challenging the traditional concept that symmetric synapses mediate exclusively inhibitory and asymmetric exclusively excitatory transmission. Furthermore, although our comparative analysis confirms considerable similarities in the distribution of CCK-containing elements in primate and rodent hippocampus it also revealed a potentially important difference in synaptoarchitecture that should be taken into account in extrapolations from one species to the other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570293
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  • 7
    Electronic Resource
    Electronic Resource
    Local circuit neurons in both the dentate gyrus and Ammon's horn establish synaptic connections with principal neurons in five day old rats: a morphological basis for inhibition in early development (1989)
    Springer
    Experimental brain research 78 (1989), S. 1-9 
    Details
    ISSN: 1432-1106
    Keywords: Inhibition ; Hippocampal formation ; Development ; GABAergic neurons ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Glutamate decarboxylase (GAD)-positive and Golgi impregnated local circuit neurons of the hippocampal formation of five day old rats were examined in light and electron microscopic preparations. The ultrastructural features of these neurons were similar in both the dentate gyrus and CA1 area of Ammon's horn. Somata displayed a perikaryal cytoplasm rich in organelles but lacked organized Nissl bodies. Most nuclei showed intranuclear infoldings of varying degrees but no intranuclear sheets or rods were found. Somata and dendrites were contacted by relatively immature axon terminals that formed mainly symmetric synapses. The axons of local circuit neurons in both the dentate gyrus and Ammon's horn formed symmetric synapses with somata and dendrites of the principal neurons in these regions. Thus, both GAD-positive and Golgi-impregnated terminals of local circuit neurons were observed to form synapses with pyramidal and granule cells. These terminals were usually small and contained relatively few pleomorphic synaptic vesicles. The results show that a circuitry for inhibition is established in the 5 day old dentate gyrus and Ammon's horn, even though the local circuit neurons lack some of the typical adult ultrastructural features at this age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230680
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  • 8
    Electronic Resource
    Electronic Resource
    Characterization of input synapses on intracellularly stained neurons in hippocampal slices: an HRP/EM study (1989)
    Springer
    Experimental brain research 75 (1989), S. 327-334 
    Details
    ISSN: 1432-1106
    Keywords: HRP-intracellular staining ; Hippocampal slice ; CA3 pyramidal neurons ; Dentate granule cells ; Input synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study describes the fine structure of input synapses on identified neurons in slices of the guinea pig hippocampus. For morphological identification, granule cells of the fascia dentata and pyramidal neurons of regio inferior of the hippocampus were impaled and intracellularly stained with horse-radish peroxidase (HRP). Input synapses on the HRP-stained neurons were identified in the electron microscope by the location of the synapses in inner or outer zones of the dentate molecular layer, as in the case of the synaptic contacts on injected granule cells, or by unique fine structural characteristics, as in the case of the giant mossy fiber boutons on CA3 pyramidal cells. As in tissue fixed in situ by transcardial perfusion, a large number of terminals arising from the different afferents in inner and outer zones of the dentate molecular layer were well preserved and formed synaptic contacts with small spines, large complex spines, and dendritic shafts of the HRP-filled granule cells. Mossy fiber synapses on the stained CA3 neurons were densely filled with clear vesicles, contained a few dense-core vesicles, and formed synaptic contacts with large spines or excrescences. Occasionally electrondense degenerating boutons were also found impinging on the stained dendrites and spines. The significance of the present findings for electrophysiological and pharmacological studies on brain slices is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247938
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  • 9
    Electronic Resource
    Electronic Resource
    Mossy fiber synapses on glutamate decarboxylase-immunoreactive neurons: evidence for feed-forward inhibition in the CA3 region of the hippocampus (1989)
    Springer
    Experimental brain research 75 (1989), S. 441-445 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampal mossy fibers ; GABAergicneurons ; GABAergic inhibition ; EM immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Mossy fibers are known to form excitatory synapses on pyramidal neurons in regio inferior of the hippocampus. This study demonstrates that the mossy fibers also establish synaptic contacts with glutamate decarboxylase-immunoreactive, supposedly GABAergic inhibitory neurons in the CA3 region. The observed connection provides a morphological basis for feed-forward inhibition of the pyramidal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247950
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  • 10
    Electronic Resource
    Electronic Resource
    Catecholaminergic innervation of pyramidal and GABAergic nonpyramidal neurons in the rat hippocampus (1988)
    Springer
    Histochemistry and cell biology 88 (1988), S. 313-319 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study describes the catecholaminergic innervation of rat hippocampal neurons at the electron microscopic level by using an antibody against tyrosine hydroxylase (TH) and immunocytochemical techniques. In a first series of experiments, the course and distribution as well as the synaptic contacts of TH-immunoreactive fibers were analyzed with the peroxidase-antiperoxidase (PAP) method. Next, peroxidase immunostaining of TH fibers was combined with glutamate decarboxylase (GAD) immunostaining, using avidinated ferritin as a second electrondense marker. Our results demonstrate that TH-immunostained terminals establish asymmetric synaptic contacts with spines of pyramidal neurons, and symmetric synaptic contacts with cell bodies and dendritic shafts of ferritin-labeled GAD-immunoreactive nonpyramidal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570289
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